The present invention is directed to methods and devices for occluding a patient's ascending aorta and returning oxygenated blood to the patient when the patient is supported by a bypass system. The invention is particularly useful when performing surgery on the heart and great vessels.
In conventional open heart surgery, the patient's heart is accessed through a large opening in the patient's chest, such as a median sternotomy. With the patient's heart exposed, various catheters, cannulae and clamps are applied directly to the patient's heart and great vessels. Blood is withdrawn from the patient through a venous cannula and returned to the patient through an arterial return cannula which is typically inserted through a pursestring suture in the ascending aorta. The heart is arrested by infusing a cardioplegic fluid into the ascending aorta with a needle. The ascending aorta is typically occluded with an external cross-clamp around the ascending aorta to isolate the coronary arteries from the remainder of the arterial system.
Recent developments in cardiac surgery have provided cannulae and catheters for occluding a patient's ascending aorta, returning oxygenated blood to the patient, and delivering cardioplegic fluid to the patient without requiring direct access to the patient's heart. Such systems are described in U.S. Pat. Nos. 5,584,803, 5,478,309 and Re. 35,352. The devices and methods described in these patents enable surgeons to perform various procedures on the patient's heart and great vessels, such as bypass grafting and valve replacements, without requiring a large opening in the patient's chest. Such procedures reduce the pain and trauma suffered by the patient as compared to traditional open-heart procedures.
Another advantage of the systems described in U.S. Pat. Nos. 5,584,803, 5,478,309 and Re. 35,352 is that occlusion of the aorta is accomplished with a balloon positioned in the aorta rather than an external clamp around the aorta. Use of a balloon to occlude the ascending aorta may reduce the amount of emboli released into the bloodstream as compared to external cross-clamps thereby reducing stroke incidents.
Although the systems described above enable a wide range of surgical procedures on a stopped heart, positioning of the aortic occlusion balloon is often challenging since the balloon must be positioned in a relatively small space between the aortic valve and brachiocephalic artery. Inadvertent occlusion of the brachiocephalic artery is dangerous since the right carotid artery, which branches off the brachiocephalic artery and provides blood to the patient's brain, would also not receive oxygenated blood. Positioning of the balloon is particularly challenging when performing aortic valve procedures since the balloon must be positioned far enough from the aortic valve to permit the surgeon to perform the procedure on the aortic valve without interference from the balloon.
Thus, an object of the present invention is to provide an aortic occlusion catheter having an occluding member which may be easily positioned within a patient's ascending aorta.